feat: add NixOS deployment infrastructure

- Nix installation guide for container (docs/nix-container-install.md)
- Deployment helper script (scripts/deploy.sh)
- SSH configuration template (scripts/deploy-ssh-config)
- Deployment skill for Hermes (skills/nixos-deploy/)

Enables remote NixOS deployment from Hermes container to target hosts
via SSH with nixos-rebuild --target-host.

Usage:
  ./scripts/deploy.sh <hostname> [branch] [action]

Supported hosts:
  - lazyworkhorse (x86_64)
  - cyt-pi (aarch64)
  - uConsole (aarch64) - config pending

scripts/deploy-ssh-config

@@ -0,0 +1,30 @@
+# Hermes Container SSH Configuration
+# For NixOS deployment to remote hosts
+
+Host lazyworkhorse
+    HostName localhost
+    User gortium
+    IdentityFile /opt/data/home/.ssh/id_hermes_gitea
+    StrictHostKeyChecking no
+    UserKnownHostsFile /dev/null
+
+Host cyt-pi
+    HostName cyt-pi.local
+    User thierry
+    IdentityFile /opt/data/home/.ssh/id_hermes_gitea
+    StrictHostKeyChecking no
+    UserKnownHostsFile /dev/null
+
+Host uconsole
+    HostName uconsole.local
+    User thierry
+    IdentityFile /opt/data/home/.ssh/id_hermes_gitea
+    StrictHostKeyChecking no
+    UserKnownHostsFile /dev/null
+
+# Generic pattern for .local hosts
+Host *.local
+    User thierry
+    IdentityFile /opt/data/home/.ssh/id_hermes_gitea
+    StrictHostKeyChecking no
+    UserKnownHostsFile /dev/null